A channel allocation to a new path in WDM (Wavelength Division Multiplexing) has been made by allocating to a new path a channel having the lowest channel (CH) number among unused channels consecutive in a section from the start point to end point of the new path.
A conventional channel allocation to a new path will now be described by way of an example. FIG. 17 is a view illustrating one example of how to select a CH number. The example of FIG. 17 illustrates used sections and unused sections of each channel between Site 1 to Site 8. A used section refers to a section already used by other paths. An unused section refers to a vacant section not used by other paths. For example, CH1 has a used section between Site 1 to Site 2, a used section between Site 7 to Site 8, and an unused section between Site 2 to Site 7. CH2 has a used section between Site 1 to Site 3, a used section between Site 7 to Site 8, and an unused section between Site 3 to Site 7. CH3 is a channel for which all sections are unused.
In the conventional channel allocation, for example, plural channels for which a section corresponding to a new path is unused are selected and a channel having the lowest CH number among the selected plural channels is allocated to the new path. For example, as illustrated in FIG. 17, CH1, CH2, and CH3 for which a Site 4 to Site 6 section used by a new path (1) is unused are selected. Then, among the selected channels, CH1 having the lowest CH number is allocated to the new path (1).
Related technologies are disclosed in, for example, Japanese Laid-Open Patent Publication No. 2006-025014.